Continual Cell Deformation Induced via Attachment to Oriented Fibers Enhances Fibroblast Cell Migration

Abstract

Fibroblast migration is critical to the wound healing process. In vivo, migration occurs on fibrillar substrates, and previous observations have shown that a significant time lag exists before the onset of granulation tissue. We therefore conducted a series of experiments to understand the impact of both fibrillar morphology and migration time. Substrate topography was first shown to have a profound influence. Fibroblasts preferentially attach to fibrillar surfaces, and orient their cytoplasm for maximal contact with the fiber edge. In the case of en-mass cell migration out of an agarose droplet, fibroblasts on flat surfaces emerged with an enhanced velocity, v = 52μm/h, that decreases to the single cell value, v = 28μm/h within 24 hours and remained constant for at least four days. Fibroblasts emerging on fibrillar surfaces emerged with the single cell velocity, which remained constant for the first 24 hours and then increased reaching a plateau with more than twice the initial velocity within the next three days. The focal adhesions were distributed uniformly in cells on flat surfaces, while on the fibrillar surface they were clustered along the cell periphery. Furthermore, the number of focal adhesions for the cells on the flat surfaces remained constant, while it decreased on the fibrillar surface during the next three days. The deformation of the cell nuclei was found to be 50% larger on the fiber surfaces for the first 24 hours. While the mean deformation remained constant on the flat surface, it increased for the next three days by 24% in cells on fibers. On the fourth day, large actin/myosin fibers formed in cells on fibrillar surfaces only and coincided with a change from the standard migration mechanism involving extension of lamellipodia, and retraction of the rear, to one involving strong contractions oriented along the fibers and centered about the nucleus.

Squish and squeeze — the nucleus as a physical barrier during migration in confined environments

“…Besides micropillars, polymer scaffolds, and electrospun matrices [25,26,79,80], microfluidic devices made from polydimethylsiloxane (PDMS) by soft lithography [81,82] have proven particularly powerful in investigating cell migration through tight spaces by providing precisely defined microscale structures and constrictions with cross-sections from 100 µm 2 to less than 5 µm 2 [15–21,23,24,64,66,83]. These devices, which often include features to apply stable chemotactic gradients [14–16,18,19,24], allow for user defined geometries ranging from simple straight channels [15,16,24,66] to more intricate designs mimicking physiological environments [18–21,23,83].…”

Biomaterial microarchitecture: a potent regulator of individual cell behavior and multicellular organization

“…• migration speed is dependent upon the specific material and its organization, with aligned fibers facilitating contact guidance…”

Tissue engineering approach using fibrous scaffold with matricellular protein for wound healing

“…The underlying mechanisms of these interesting phenomena were speculated to be due to the focal adhesion assembly as well as Rho small GTPase activity. As similarly reported in other literature [192], lower expression of focal adhesions was observed on cells cultured on aligned fibers. Additionally, it has been well accepted that adhesion strength influences the speed of cell motility [163].…”